In a mobile terminal, there are generally two processors. One of them is an application processor (AP), which is mainly used for processing Android applications. The other one is a baseband processor (BP), which is mainly used for processing communications with base stations.
At present, owing to the popularity of VoLTE/VoWiFi functions, the IMS support required by them is basically a function that mobile terminals must support in the future. Almost all operators now require the terminal to support the IMS protocol so as to meet the demand for the terminal to support VoLTE/VoWiFi.
Due to the differences among networks, and the fact that the specification does not impose requirements on many configurations of the IMS, how to implement the terminal IMS configuration to be complied with the network end has become a very labor-intensive process when a mobile terminal manufacturer ships a single product to multiple operators.
For a mobile phone, the current platform vendors' scheme for implementation of IMS configuration is generally:
Presetting IMS configuration of a known operator at a BP end is as follows. When a SIM card is inserted into the mobile phone, according to a mobile country code (MCC) and a mobile network code (MNC) comprised in an international mobile subscriber identity (IMSI, the IMSI is a sign that distinguishes a mobile subscriber and is stored in the SIM card, it can be used to distinguish effective information of the mobile subscriber) in the SIM card, the IMS parameter number of the operator in its respective country is mapped. For example, the IMS parameter number of China Mobile is 1. Then, the AP end transmits the IMS parameter number to the BP. The BP acquires IMS parameter tables correspondingly according to the IMS parameter number. When the mobile phone is interacted with a network end, these IMS parameter tables that have been mapped to the network end are used.
For example, POP-X products of a T manufacturer need to be shipped to Orange, France and Vodafone, Germany at the same time, then the T manufacturer is required to preset IMS configurations for Orange, France and Vodafone, Germany at the BP of the mobile phone. In this manner, the demands for IMS by Orange, France and Vodafone, Germany can be met.
Under the circumstances, there will be a situation in which an operator corresponding to the MCC and MNC starts an IMS related network. For the terminal, it is necessary to access the IMS network to test and communicate with the operator so as to acquire related parameters, and then preset the related parameters at the BP end. The BP end is thus able to implement capabilities used under the network. Since codes at the BP end are generally written in C language, each parameter change requires processes including code modification, compilation and being downloaded to the mobile phone to run, which is very time consuming and labor-intensive.